Speaker



FeB. 11, 1930. H SIMPSON 1,746,289

' SPEAKER.

Filed De c. 16. 1926 2 sheets-Sheet iNVENTOR adag a.- 5M

Feb. 11, 1930 A S, P Q 1,746,289

SPEAKER Filed De c- 16, 192 2 sheets-sheep 2 INVENTOR v TORNE' I Patented Febi '11-, 19 30 UNITED STATES- ATE-NT OFFICE" HOBART A. SIMPSON, OF OCEAN GROVE, NEW JERSEY, ASSIGNOB TO ASPARAD RADIO I conronarron, or asnuny mn r, new masny SPEAKER Application filed December 16, 1928. Serial 1T6. 155,218. I

This invention relates to what are generally known as loud speakers.

The objects of the invention are to improve the tonal qualities of this class of devices, to provide a speaker which will reproduce faithfully the tone values ranging from the lowest through the highest of the audible scale, which speaker will be artistic in appearance 'as well as in the musical sense, and'furthermore, be of relatively simple, inexpensive design and structure.

The foregoing and other desirable objects are attained in part by the provision of a novel form of sounding board constructed after the manner of a piano sounding board and actuated by a telephonic unit connected with the board at a special point.

The invention comprises a number of other novel features, combination and relation of zo-parts as will be clear from the following specification.

V p The drawings accompanying and formingv part of this specification illustrate one practical embodiment of the invention; It should be understood, however, that the structure may be modified and changed in certain respirit and scope of the invention as hereinafter defined and claimed. 1

Figure 1 is a front or face viewof the complete speaker.

Figure. 2 is anenlarged vertical sectlonal view of the same as on substantially the plane of line 22 of Figure 1. Figure 3 is a further enlarged broken sectional detail of the connection between the actuating in board. I

Figure 4 islarear view of the speaker. Figure 5 is an enlarged horizontalsectional viewas on the plane of line 5-5 of Figure 4. Figure 6 is a detail illustrating a form of resilient connection with the board.

The sound wave creating member is herein disclosed as a wooden sounding board 7, widest at the bottom and tapered to a point at the top, in the general shape of a Gothic arch. This board is shown as made up of diagonally laid thin strips of-spruce or the like secured inintegrally united edge to edge tral and side ribs 12, 13, 14 on the back and and as having materially reduced flattened unit and the diaphragm or sound relation on a correspondin ly shaped frame 8. These strips may be of tie same'or of different widths but some advantages follow from the use of wider strips at the lower end and central portion of the board and narrower strips toward the top of the board, as indicated inthe illustrations. In making up the board the strips are secured undercompression and the board 'in its final form is held by the frame under a certain amount of compression, rendering it alive or particularly sensitive to vibrational forces. The shape of the board, widest at the base, and narrowing toward the top imparts to it the desired tonal characteristics, as the lower portion bringing out the bass notes i and the intermediate and upper portions bringing out the treble or high notes. This compressive force has a tendency to buckle the board outwardly, as indicated clearly in Figures 2 and 5.

. The board is braced and further unified in the illustration by two systems of ribs, a central long rib 9 and two shorger side ribs 10, 11 on the face thereof'and cor espdnding cenimmediately opposite the first set. These ribs may be secured by gluing or otherwise and they are shown shaped in the manner of, trusses, tapered toward their opposite ends so or thin end portions15 forming in effect flexible tongues. These ribs, it will be noted, terminate an appreciable distance inward from the frame and the flexible tips are of appreciable length. Thelength and spacing of these ribs; it will be noted 'inFigures 1 and 4, is such as to define a braced central portion of the board of substantially the same out- 1 line as the complete board and spaced in- 90 wardly an equal distance from all edges of i the board. The length of the ribs determines the natural tone of the board. and the board is preferably tuned in this fashion to G natural in the intermedmte scale, as when so termediate diaphragm portion outlined or defined by the ribs and at a point equal distances inward from the sides and the lower end of the same. This connection is shown as made by a headed screw stud 16 extending through the two central ribs 9, 12 and held clamped to the board by a nut 17 whichcan be fixed in adjusted relation by set screw 18. Beneath the head .of the stud and the nut 17 cork washers 19 are interposed to prevent any localized vibrations and thin fibre washers 19 prevent abrasion.

The stud is shown as connected with the actuating unit 20 by an impulse transmitting rod 21 and in order that the relation of the board and unit may be readily adjusted this rod is shown as having a fine screw thread 22 entered in the end of the stud and the head of the stud is shown as slotted at 23 so that the same ma be readily turned with a screw driver to bring the board and unit into proper relative position.

The unit is suitably mounted to actuate the board. In the present instance it is shown as carriedby a bridge attached at its ends to the sides of the frame. In Figures 4 and 5 this bridge is shown as made up of arched strips 24.overlying and connected with the tension. strips 25 by inclined struts 26. Attached to the arches beneath the struts 26 is a supporting plate 27 to which the o erating unit is secured by screw means 28. his construction provides a light but rigid bridge. This bridge 1s shown secured to the frame by through screws 29. Washers 30 of rubber or other suitable material are shown provided at the opposite ends of thesesecuring screws.

The bridge for supporting the unit may be of cast metal or may be of wood. In the latter case the same may be secured rigidly to the frame without the interposition of any insulating washers.

The actuating unit ma be supported separate and apart from the card and its frame, for example, by means of a cabinet or enclosing structure, when the board is mounted in a cabinet. The cabinet may be constructed as a sound chamber for the board and the board be fixedly mounted in the cabinet. The connection of the unit with the board at a central point approximately one-third the height of the board appears to utilize the full roperties of the board to the best effect. he. bass tones may be'incre'ased by thinning'the ends of the ribs more and this, with the regulation of the length and number of the ribs provide a method of control for securing difie'rent desired eflects.

The use of the cork washers at the point of connection with the board enables the board to be properly gripped without choking oil the sound values. These washers interpose a certain de ree of resiliency and this resiliency may be urther increased by employing a construction such as illustrated in Figure 6 where the connection with the board is made through the agency of a somewhat flexible tongue 31 secured in spaced relation to the back of the main rib by a block 32, this tongue being gripped between the cork washers as before and the shank of the stud 16 projecting freely through a bore 33 provided clear through the board and ribs.

What is claimed is:

.1. A speaker comprising a wooden board under compression and having the general shape outlined by a Gothic arch and an actuating unit connected with the median portion of the board at a point substantially onethird the distance from the base to the peak of the arch.

2. A speaker comprising a wooden board under compression and having the general shape outlined by a Gothic arch and an actuating unit connected with the median portion of the board at a point substantially one-third the distance from the base to the peak of the arch, said board having a central rib and the connection for the unit being made with said rib.

3. A speaker comprising a Wooden board under compression and having the general shape outlined by a Gothic arch, an actuating unit connected with the median portion of the board a a point substantially one-third the distance from the base to the peak of the arch, said board having a central rib and the connection for the unit being made with said rib, a frame for the board and a bridge across said'frame and forming a mounting for the actuating unit.

4. A speaker comprising a wooden board under compression and having the general shape outlined by a Gothic arch, an actuating unit connected with the median portion of the board at a point substantially one-third the distance from the base to the peak of the arch and resilient means interposed at the connection between the unit and board.

5. A speaker comprising a wooden board under compression and having the general shape outlined by a Gothic arch, an actuating unit connected with the median portion of the board at a point substantially one-third the distance from the base to the peak of the arch and a resilient tongue interposed at the connection between the unit and board, said tongue being secured in spaced relation to the board.

'6. A speaker comprising a thin wooden board under compression taperin in width toward one end and having a rein orcing rib of less than the full length of the board and a telephonic unit connected with said board.

7. A speaker comprising a thin wooden board under compression tapering in width toward one end and having a reinforcing rib of less than the full length of the board and a telephonic unit connected with said board through the agency of said rib.

8. A speaker comprising a' thin woodenboard under compression tapering in width toward one end and having a reinforcing rib of less-than the full length of the board, a telephonic unit connected with said board and a resilient element interposed at the connection between the unit and the board.

9. A speaker comprising a thin wooden board'under compression tapering in width toward one end and having a reinforcing rib of less than the full length of the board, a telephonic unit connected with said board and a resilient cork-like medium interposed at the connection between the unit and board;

10; A speaker comprising a thin wooden board under compression tapering in width toward one end and having a reinforcing rib of less than the full length of the board and a telephonic unit connected with said board, the connection between board and unit .including, screw means, adjustable to vary the relation'between the two, said screw means having a rotatably cushioned mounting on the boardr 11. A speaker comprising a frame, a wooden board supported by said frame, a brid e secured to the frame and extending across the board and a telephonic unit mounted on said with an intermediate portion of said sound- 7 ing board.

16, A speaker comprising a relatively rigid supporting frame, a flexible soundin board wooden board, a bridge construction extending in spaced relation across the face of said board, a telephonic speaker unit mounted on said bridge and a variable operating connection from said speaker unit to an intermediate portion 'of said board and including a drivv ing rod connected with the board so as to positively vibrate the same.

In witness whereof, I have hereunto set my hand this 29th day of November, 1926. 1 HOBART A; SIMPSON.

bridge and havinga variable connection with an intermediate portion of the board.

- 12. A speaker comprising a board, a telephonic unit having'an actuating rod with a fine screw thread, a stud'having a screw seat for: said screw threaded rod and means for adjustably clamping said stud to the board, including resilient cork-like washers interposed between the board and opposite end portions of the stud."

13. A speaker comprising a board, a screw .studcxtending' through said board with a head at one side of the board, a nut on the screw stud at the opposite side of the board,-

cork-like washers beneath said nut and the head of the stud, a telephonic unit having an actuating rod and a fine pitch screw connection between the stud and said rod.

' 14. A speaker comprising a board, a screw stud extending through said board with a head at one side of the board, a nut on the screw stud at the opposite side of the board,

cork-like washers beneath said nut and the head of the stud, a telephonic unit having an actuating rod and a fine itch screw conneotion between the stud an said rod, said stud being rotatable in the board to adjust the connection with the rod and friction reducing washers between the head of the stud and the cork-like washer at one side of the board and between the nut andnthe cork-like washer at the other side of the board.

15 A speaker comprising a relatively rigid supporting frame, a flexible sounding boardcarried by said frame, a bridge carried by and extending across said frame and a telephonic speaker' unit having a variable connection 

